1. Technical Field
Photoresist polymers and photoresist compositions containing the same are disclosed that can improve profile of a photoresist pattern, without the need for any dummy patterns and which improve etch resistance during pattern formation.
2. Description of the Related Art
As manufacturing processes of semiconductor devices become more complicated and the degree of integration increases, methods for forming fine patterns are needed. Since it is difficult to obtain a fine pattern with conventional photolithography using KrF (248 nm), photolithography using far-infrared light source such as ArF (193 nm) has been developed. However, photoresist materials that have been used in ArF photolithography are more difficult to use than conventional photoresist materials. Specifically, as the critical dimension CD has been decreased by the high integration of semiconductor devices, the aspect ratio of a pattern is increased which can cause collapse the photoresist pattern 12 on the semiconductor substrate 11 as shown in FIG. 1.
There are many processes for forming layers of semiconductors. As the size of a pattern becomes smaller, a pattern in the outer region of a field or a block becomes remarkably smaller because the pattern in the outer region receives a relatively larger amount of light energy in comparison with the inside of the field of the block where patterns are arranged more uniformly and densely.
In order to prevent the outer portions of the pattern from being reduced in size, the amount of energy or an exposure condition of lens has been regulated. However, this conventional method does not solve the problem.
In addition, problems arise when the margins of DOF (Depth of Focus) and EL (Energy Latitude) become smaller as the pattern becomes smaller. However, these problems cannot be solved by using the change of exposure conditions. Also, it is difficult to secure etching resistance because the thickness of the photoresist film is reduced to prevent pattern collapse.